Objective  To explore effects of different dimensions of family sports environment on physical activity (PA) among Chinese adolescents and to provide evidences for developing family-based PA promotion strategies in the future.

  Methods   Using randomly sampling at 4 urban high schools in two municipalities (Beijing and Shanghai) and two provinces (Shandong and Shaanxi), we recruited 320 healthy adolescents aged 14 – 18 years and in two-parent families. The students′ time for physical activity of various intensity during previous one week were determined with ActiGraph WGT3X-BT three-axis accelerometer and the information on students′ family sports environment were collected with a questionnaire survey self-administrated by the students′ parents.

  Results   For the 314 adolescents with complete information, the weekly time (minutes) of sedentary behavior (SB), light-intensity physical activity (LPA), and moderate-vigorous intensity physical activity (MVPA) were 5 016.33 ± 1 872.00, 338.03 ± 215.60, and 1 585.24 ± 896.22. The adolescents′ scores for family-based PA availability and accessibility were 12.62 ± 3.65 and 7.83 ± 3.52; the adolescents′ scores for parental PA modeling and encouragement were 15.69 ± 5.28 and 22.29 ± 6.62 and those for maternal PA modeling and encouragement were 16.74 ± 4.11 and 8.64 ± 3.17, respectively. Compared to the adolescent girls, the adolescent boys had significantly higher weekly time of LPA and MLPA, higher scores for family-based PA availability and accessibility, and higher scores for parental and maternal PA modeling and encouragement (all P < 0.01) but lower score for SB. The results of the multivariate linear regression analysis demonstrated that: the major influential factors of SB included (1) family-based PA availability, maternal PA modeling and encouragement for all adolescents, (2) family-based PA availability, parental and maternal PA modeling, and maternal PA encouragement for adolescent boys, and (3) family-based PA availability and maternal PA encouragement for adolescent girls; the major influential factors of LPA were family-based PA availability and maternal PA encouragement for all adolescents and adolescent boys, and family-based PA availability and parental PA encouragement for adolescent girls; and major influential factors of MVPA included (1) family-based PA availability and maternal PA encouragement for all adolescents, (2) family-based PA availability and maternal PA modeling for adolescent boys, and (3) parental PA encouragement for adolescent girls, respectively.

  Conclusion   The PA of urban adolescents is closely related to family-based PA environment and the social environment and the results should be concerned in promoting PA among adolescents.